Electronic housings are known which include a mounting plate on which are mounted a first detector microchip provided with a first and a second light radiation sensor and a second emitter microchip provided with a light radiation emitter and which include an encapsulation cover for the chips.
This cover includes a peripheral wall, a front wall and an inside partition locally passing above the first chip, between its sensors. The partition delimits two cavities so that the emitter of the emitter chip and the first sensor of the receiver chip are located in one of the cavities and the second sensor of the receiver chip is located in the other cavity. The front wall of the cover has an opening facing the emitter of the emitter chip and an opening facing the second sensor of the receiver chip, in which optical elements such as glass plates or optical lenses are placed. Generally, the cover is attached to the mounting plate and to the receiver chip by means of a bonding material. The cover and the bonding material are opaque.
Thus, the light radiation from the emitter chip is emitted towards the outside, the first sensor of the receiver chip captures the light radiation from the emitter chip in the corresponding cavity and the second sensor of the detector chip captures the outside light radiation. A proximity detector may thus be produced in which the signals from the sensors of the receiver chip are processed for detecting the presence or absence of an object in front of the housing. Such a proximity detector may be fitted in a mobile phone, for example, for automatically turning off the screen when the latter is close to a user's ear.
During manufacture, beads of bonding material are spread over the support plate and on the chip and the cover is placed on these beads. Nevertheless, due to the difficulties of calibrating the beads, several drawbacks appear.
There is a risk that the bonding material, interposed between the partition and the receiver chip, creeps by capillarity until it reaches and corrodes the front connecting pads of the chip, and/or until it at least partially covers at least one of the sensors of this chip, so that this sensor is no longer capable of correctly detecting the light radiation. The bonding material may also creep, by capillarity, along the internal walls of the cover, until it reaches the optical elements placed in the openings of the front wall of the cover. In the event of discontinuity in the bonding material, the light radiation present in one of the cavities may penetrate into the other cavity, so that the light radiation detection by the sensors of the receiver chip is distorted. In addition, the strength of the cover attachment, notably of its partition on the receiver chip, is unpredictable.